JPS6332107A - Turning system of turbine - Google Patents

Abstract

PURPOSE: To enable a turbine to be started at a high increasing rate of rotational frequency by varying the rotational frequency for its turning and the preset value of feed oil temperature during its turning according to a target rotational frequency increasing rate which is determined through judging from the stopping time of the turbine. CONSTITUTION:The oil temperature in the oil feeding and draining systems 1, 2 of a turbine is controlled by means of a control device (PID) 4 in such a way that the quantity of cooling water fed to an oil cooler is regulated. Corresponding to the stopping time of the turbine, a target rotational frequency increasing rate and a feed oil temperature set value are selected. That is, when the stopping time is within a fixed period of time, the rotational frequency increasing rate is set at a high value, and at the same time, the rotational frequency for its turning is also set at a high value, and then, the bearing oil temperature is set at a high temperature. Hereby, the turbine can be started at a high increasing rate of rotational frequency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a turbine turning method that changes the bearing oil supply temperature according to the operating condition, and in particular, the present invention relates to a turbine turning method that changes the bearing oil supply temperature depending on the operating condition, and in particular, it is possible to start at a high rotation speed increase rate by shortening the startup time. This article relates to turbine turning methods that may be required.

[Conventional technology]

Taking a thermal power plant as an example, a turbine bearing oil supply/drainage system and an oil supply temperature control system are schematically shown in FIG. 1.

In the figure, numeral 1 indicates the oil supply system for the turbine.

2 is an oil drainage system, and 3 is a cooling water system that cools the oil supply.

Reference numeral 4 denotes a bearing oil supply temperature control device, which is a normal temperature controller that maintains the oil supply temperature at a set temperature when a set temperature is applied. In these systems and devices, the turbine bearing oil supply temperature is conventionally controlled as shown in FIG. 2 according to the operating condition of the turbine. That is, the following is as follows: 1) The oil supply temperature during turning operation from the turning engagement after the turbine is stopped to the turning disengagement at the next startup is:
Turning speed: 2 rpm (Normally, turning speed is independent of start and stop modes (constant around 2 rpm), but in order to optimize the formation of an oil film on the bearing, the turning speed is controlled to be constant at around 32 degrees Celsius regardless of the turbine start and stop modes. (As the temperature rises, the viscosity of the oil decreases, causing chatter and vibration.)

2) The oil supply temperature while the turbine rotation speed is increasing from leaving the turning to reaching the turbine rated rotation speed is changed linearly between the oil supply temperature at turning of 32℃ and the oil supply temperature at the rated rotation speed of 46℃ (described later). is used as a target value for temperature control, but in reality, even if the cooling water valve is fully closed by control, the temperature of the drained oil does not rise due to turbine bearing loss as shown in the figure (no heating is done in the oil tank, etc.). (No.) The actual oil temperature cannot catch up with the set temperature and is quite behind. On the other hand, the conditions for achieving the rated rotation speed are 3.
Since the temperature is 8° C., if the temperature cannot be obtained when the rated rotational speed is reached by control, a rotational speed increase rate higher than that which satisfies that condition cannot be selected.

3) The oil supply temperature during operation of the turbine at the rated rotational speed, including load operation from merging to decoupling, is controlled to be constant at about 46° C. regardless of the startup/stop mode of the turbine.

4) The oil supply temperature while the turbine rotation speed is decreasing from parallel separation and turbine trip to turning feed is determined by changing linearly between the oil supply temperature at rated rotation speed of 46°C and the oil supply temperature at turbine time of 32°C. This is the target value for control, and it is controlled satisfactorily.

As shown in 1), the turbine turning method is always 2rPIl+turning regardless of the turbine start/stop mode, and no particularly unusual method is used.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not give sufficient consideration to the current needs for turbine operation, such as shortening the startup time by starting and stopping each time and reducing startup loss. That is,
In an attempt to start the turbine at a high rotation speed increase rate, the turbine bearing oil supply temperature setting was changed from 32℃ at turning to 46℃ at rated rotation speed, and even when the turbine was started, the actual oil temperature was lower than the set temperature. The problem is that the engine speed cannot catch up and the rotation speed cannot be increased to the rated value.

The first method can be considered as a countermeasure to this problem, but in either case, there are problems listed below and it is difficult to say that it is a good solution.

1. It may be possible to use a dedicated oil supply system to heat the heating device, but this method requires very complicated equipment and has economical problems, as well as lack of experience and disadvantages in terms of reliability. It is.

2. Even when starting at a high rotation speed increase rate (generally around 360 rpm), always adjust the oil supply temperature during turning to the point where the specified actual oil temperature is obtained when the rated rotation speed is reached, taking into account one of the following: A possible method is to raise the temperature (about 37°C), but each method has the following problems.

a) Since the viscosity of the oil decreases as the oil temperature rises, one possible method is to install a jacking oil pump separately from the bearing oil supply pump, which uses high-pressure oil to jack up the turbine shaft and supply oil for smooth turning operation. However, this method also requires very complicated equipment and requires economical time, and at the same time, there are problems in terms of ease of procurement and maintenance since the pumps are generally imported products.

b) Figure 3 shows the relationship between oil film thickness and changes in oil supply temperature and rotational speed. If turning is performed at low rotational speed with high oil temperature, the minimum required oil film thickness cannot be secured, and the shaft and bearing Since this introduces metal contact and causes damage, it is possible to measure the oil model as high rotational speed turning of 5 to 6 rpm during separation when the viscosity of the oil decreases, but high rotational speed turning is different from normal rotational speed turning. It is disadvantageous in the following points,
There is a problem with constantly turning at high rpm throughout the year.

Reasons why turning at high rotational speeds is more disadvantageous than normal rotational speeds 1) When foreign matter gets mixed into the bearing (contaminants in oil), the rotational energy of the turbine shaft is large, resulting in greater damage to the bearing.

2) The number of times the field coil, which is housed in the slot in the generator rotor body, moves due to its own weight increases, and the generation of copper powder due to the rubbing of copper between layers increases significantly.

Figure 4 is a cross-sectional view of a gear pickup type rotor slot that is most commonly used in large capacity machines, with 1 being a wedge, 2 being a clipage block, 3 being a slot liner, and 4 being a wedge.
is the turn insulation, and 5 is each turn composed of multiple layers (
2-split conductor), 6 is a ventilation hole, and the generation of copper powder is due to the relative deviation between the coppers between the eyebrows of each turn of 5, which is caused by the movement due to its own weight during turning. It happens. Therefore, at the rated rotation speed, etc., they are locked by centrifugal force and there is no mating, and no copper powder is generated.

Note that an increase in copper powder may cause grounding accidents. (Actually, accidents have been reported in some cases.) 3) In general, the results of the turbine shaft and turning device gears tend to come out of alignment.

The object of the present invention is to set the turbine bearing oil supply temperature during turning to the normal setting when the turbine starts at a normal rotation speed increase rate, and to set the turbine bearing oil supply temperature during turning only when the turbine starts at a high rotation speed increase rate. The object of the present invention is to provide a turbine turning method that allows the turbine to be set at a high level.

[Means for solving problems]

The above purpose uses a turning device that can switch the turning speed in multiple stages.

The startup mode for the next turbine startup is estimated from the turbine stop time. This can be easily done by using the casing metal temperature cooling curve and estimating the amount of temperature drop from the current stop time.

If the rotation speed increase rate is high (such as when starting up within 8 hours after stopping the turbine), set the bearing oil supply temperature during turning to a high temperature setting and also set the turning rotation speed to a high rotation speed to prevent oil film formation. Conversely, if the rate of increase in rotational speed is the normal rate of increase (such as when starting the turbine 8 hours or more after it has stopped), set the bearing oil temperature and constant to the normal setting, and set the turning rotational speed to the normal rotational speed. is achieved.

[Effect]

If the rotational speed increase rate at the next turbine startup is a high rotational speed increase rate, the oil supply temperature during turning is set to a high temperature and the turning rotational speed is set to a high rotational speed, but each of these functions has the following functions.

1) If the oil supply temperature during turning is set to a high temperature, the difference from the oil supply temperature at the rated rotation speed is small, so the turbine can be started at a high rotation speed increase rate (because the turbine will cool down if the turbine is stopped for a long time) Even if the temperature is set to a high temperature, the oil supply temperature does not rise.However, in this case, it is impossible to start the turbine at a high rate of increase in rotational speed from the viewpoint of thermal stress, and there is no need to set a high temperature.

).

2) If the turning rotation speed is also set to a high rotation speed, the generated oil pressure is increased due to the pump action effect due to rotation and an oil film is formed, so turning can be performed at a relatively high oil temperature.

〔Example〕

Hereinafter, the present invention will be explained based on examples. An embodiment to which the present invention is applied is shown in FIG. 1 and FIGS. 5 and 6.

First, as mentioned above, FIG. 1 shows the turbine bearing oil supply/discharge system and the oil supply temperature control system, and 5 shows the oil supply temperature control setting switching circuit during turning according to the present invention.

Next, FIG. 5 is a schematic diagram of a turning device according to the present invention, which uses an AC motor as a drive source and is capable of changing the turning speed in two stages by changing the number of poles. In this figure, 1 is a gear for coupling with the turbine shaft, 2 is a two-unit electric motor for driving a turning device, and 3 is a contactor for switching the number of poles of the motor. Turning speed can be selected.

Furthermore, Fig. 6 shows that when the turbine rotation speed increase rate at the next turbine startup is high, the oil supply temperature setting is set to a high temperature and the system automatically switches to high rotation speed turning (the turbine rotation speed increase rate is high). In the case of the normal rotation speed increase rate, the oil supply temperature setting is set to the normal temperature setting and the normal rotation speed turning is selected.) The sequence logic is shown below.

In this figure, 1 is an AND logic, 2 is an OR logic, 3 is a NOTOR logic is a timed operation timer, 5 is a keep relay, 6 is a contactor shown in Fig. 4 and 3, and 7 is a turning command signal of 8 for the first time. A circuit that forcibly selects low rotational speed turning (for about 10 seconds) while the timed operation timer in step 4 counts up when it is established (if turning is started at high rotational speed turning, the turning coupling is particularly likely to come off, It is preferable to turn at a low rotation speed.)

9 is after the turning command signal is established and the specified time has elapsed (4
10 is a circuit that selects normal rotational speed turning when the turbine normal rotational speed increase rate startup is selected (timed operation timer count up), and 10 selects high rotational speed turning when a high rotational speed increase rate is selected. The circuit 11 is the circuit shown in FIG. 1 and 5, and is a circuit for switching the oil temperature setting in the same manner as described above. In addition, there is a contact point 12 that outputs an output corresponding to the rotation speed increase rate at the next turbine startup determined from the turbine stop time. Specifically, from the turbine casing metal temperature cooling curve in Figure 7, the output is determined from the turbine casing metal temperature cooling curve at the next turbine startup. The metal temperature is determined, and the rotation speed increase rate is determined in advance from the metal temperature when the turbine is started. The keep relay 5 is a circuit that holds this signal once the high rotational speed increase rate is selected until the normal rotational speed increase rate is selected (to prevent unnecessary ON-OFF repetitions).

According to this example, it is an extremely economical method (?! Because the motive power itself is small with a power of 7 to 8 kW, even a two-speed type will cost over 100,000 yen, which is by far the cheapest method compared to other methods. .)
Two-stage turning is possible, which has the effect of minimizing high-speed turning and ensuring the formation of an oil film on the shaft.

〔Effect of the invention〕

According to the present invention, in a warm-up state such as when the turbine has been stopped for 8 hours, it is possible to start the turbine at a higher rotation speed increase rate than before in a relatively simple manner. This has the effect of minimizing rotational speed turning.

[Brief explanation of the drawing]

Figure 1 is a diagram of the turbine bearing oil supply/drainage system and oil supply temperature control system, Figure 2 is a turbine startup characteristic diagram, Figure 3 is a diagram showing the relationship between oil supply temperature and oil film thickness with respect to changes in rotation speed, and Figure 4
The figure is a cross-sectional view of the generator gear pickup type rotor slot, Figure 5 is a conceptual diagram of the turning device, Figure 6 is a switching sequence logic diagram between high rotation speed and normal rotation speed turning, and Figure 7 is the turbine casing metal temperature. It is a bookkeeping curve. High 1 figure, 3 figure, 4 figure, S figure attached power supply 61 yen

Claims (1)

[Claims] 1. Turning device and turbine bearing In a turbine equipped with an oil supply temperature control device for changing the oil supply temperature according to the operating state of the turbine, a turning device that can switch the turning rotation speed in multiple stages is used,
Turbine casing metal that determines parameters for starting the turbine, such as the target rotation speed increase rate at the next turbine startup, which is determined from the turbine stop time, or the rotation increase rate, for switching the turning rotation speed and changing the control setting value of the oil supply temperature during turning. A turbine turning method characterized by turning in response to temperature or an equivalent signal.